Various ambulatory medical devices have been proposed and a number of such devices are commercially available. These devices include, for example, implantable infusion pumps, externally carried infusion pumps, implantable pacemakers, implantable defibrillators, implantable neural stimulators, implantable physiological sensors, externally carried physiologic sensors, and the like.
As appropriate operation of ambulatory medical devices may be critical to those patients being treated using those devices, and as telemetry communications between ambulatory medical devices and controllers can greatly enhance the convenience of using such devices, or even be an enabling necessity to the use of such devices (e.g. implantable devices with sophisticated functionality), the operation of such medical devices can benefit significantly by use of telemetry systems and protocols that have features/elements that lead to optimization of various attributes. Such attributes may include (1) flexibility in communicating the wide variety signals that may be useful to controlling and retrieving information from a sophisticated medical device, (2) robustness in distinguishing actual signals from noise, (3) robustness in distinguishing valid signals from corrupt signals, (4) robustness in ascertaining when appropriate communication has occurred and when additional communication must be attempted, (5) a reasonable efficiency in communication time, and/or (6) a reasonable efficiency in electrical power consumption associated with conveying information over the telemetry system.
Implantable medical devices typically operate by battery power. The batteries may or may not be rechargeable. Higher consumption of power from an implantable medical device containing non-rechargeable batteries leads to a shortening of the usable life of the device and an associated increased frequency of surgery, potential pain, recovery, and inconvenience. Higher consumption of power from an implantable medical device containing rechargeable batteries leads to more frequent charging periods for the batteries and associated inconvenience and may lead to an overall shortening of the usable life of the device. As such, whether or not an implantable medical device contains rechargeable batteries or non-rechargeable batteries, it is desirable to lower the power consumption of the device. As telemetry reception and transmission are highly energy consumptive, it is desirable to minimize the operation time of telemetry reception and transmission modules.
A telemetry reception module of a first device needs to (1) be powered to listen for potential incoming messages from a second device, (2) stay powered during the entire receipt of the message, and (3) potentially be powered one or more repeated times to receive a duplicate message when the second device is expecting a response to its original message and does not receive one. A telemetry transmission module of a first device needs to (1) be powered so it can transmit a desired message to a second device, and (2) potentially be powered one or more times to retransmit a duplicate message when the first device fails to receive confirmation that original message was received by the second device.
A need exists in the field for improved telemetry features/elements that tend to minimize one or both of power on time for telemetry reception modules and/or telemetry transmission modules to reduce power drain on batteries used in powering ambulatory medical devices and communicators. A need exists in the field to ensure that device users are not inconvenienced with long delay times that may be associated with inputting information into the communication device, transmitting information via telemetry to the medical device, and waiting for confirmation that the transmitted information was appropriately received and is was or will be appropriately acted upon.